As a follow up to our previous genetic studies both in childhood-onset and adult-onset SLE, our goal is to identify major genetic risk factors in novel genes and characterize the causal mutations and the mechanisms of disease involvement of these new genes. For the purpose of these studies we have assembled an unparalleled study population of 6,500 adult-onsets and 1,100 childhood-onset cases of SLE and a large multidisciplinary collaborative team of investigators. Based on Bayesian methodology, we developed a gene selection tool to increase the power of genetic association studies, and we devised a novel microarray platform to discover susceptibility genes contributing to SLE. We tested our model in a cohort of childhood-onset SLE families and replicated the results in a second much larger childhood-onset SLE cohort and a very large cohort of adult onset SLE. We propose to identify the causal variants in the following new genes: FAIM, IRAK1, KLRG1, TNFSF4, TLR8 and SELP by fine mapping, re-sequencing and re-evaluation of the new SNPs identified through sequencing in case-control association studies in four different ethnicities in both childhood-onset and adult-onset cohorts. Based on the variants and causal haplotype blocks found, we will conduct hypothesis-based analyses in clinical sub-phenotypes of SLE. Finally we will conduct functional studies toward understanding the mechanisms through which the genetic variants discovered and characterized in sub-phenotypes of SLE may be involved in the causation or perpetuation of SLE. We anticipate that these studies will identify novel gene variants, especially those that are common to several ethnic groups and to both childhood- and adult-onset SLE. Results of these association studies will lead to the molecular characterization of their effects on the gene products and an understanding of the role of these genes in the pathogenesis of SLE. Knowledge gained from these studies will reveal new paradigms and open promising new directions in the understanding and ultimately the treatment of this devastating disorder.